WASHINGTON -- President Obama warned Republicans on Capitol Hill, who are holding up a government spending bill in an attempt to eliminate money for the healthcare law, not to “threaten to burn the house down simply because you haven’t gotten 100% of your way. ”

“My message to Congress is this: Do not shut down the government. Do not shut down the economy,” the president said in a late-afternoon appearance in the White House briefing room. “Pass a budget on time. Pay our bills on time. Refocus on the everyday concerns of the American people.”

Obama spoke hours after the Senate passed a measure that would keep the government running until through Nov. 15, using existing spending levels and retaining budget cuts implemented earlier this year. Democrats in the chamber stripped out a measure that would have ended spending on Obamacare.

The bill faces major obstacles in the Republican-led House, where conservatives want to use Monday’s midnight deadline to pass a spending bill to achieve their long-sought goal of undermining the healthcare law. After more than three years of preparation, the centerpiece of the Obamacare program, insurance marketplaces, is due to open for business on Tuesday.

“Those marketplaces will be open for business on Tuesday, no matter what, even if there's a government shutdown,” Obama said. “That's a done deal.”

House Republican leaders were deliberating Friday on whether to attach new provisions to the Senate spending bill, such as repealing a tax on medical devices or instituting a one-year delay of the requirement that individuals have health insurance. Both measures might find support in the Senate.

Obama cast the debate as largely political posturing, accusing House Republicans of being motivated by a desire to appease the tea party. But he noted that a shutdown would have real effects, including on military families and, he noted, young congressional aides. “I realize that a lot of what’s taking place right now is political grandstanding but this grandstanding has real effect on real people,” he said.

The uncertainty just days before the deadline had some in Washington predicting that some government offices would be forced to close Tuesday, the first government shutdown since the 1996 budget standoff between President Clinton and then-House Speaker Newt Gingrich.

This one would come with a follow-up punch. On Oct. 17, when the government is due to hit the limit it can borrow unless Congress and the president agree to raise it. If that ceiling is not raised, the United States could default on its obligations. After two bruising debt ceiling fights in as many years, the White House has said it won’t negotiate with Congress on the issue.

“We're not going to do this under the threat of blowing up the entire economy,” Obama said. “I will not negotiate over Congress' responsibility to pay the bills that have already been racked up.”

Obama said the threat of a default is “far more dangerous than a government shutdown,” calling it a possible “economic shutdown” with global ramifications.

“We don’t fully understand what might happen, the dangers involved, because no Congress has ever actually threatened default,” he said. “But we know it would have a profound destabilizing effect on the entire economy, on the world economy, because America is the bedrock of world investment.”

[Updated, 1:52 p.m. PDT Sept. 27: A spokesman for House Speaker John A. Boehner (R-Ohio) responded to the president’s remarks by accusing him of playing politics. “Grandstanding from the president, who refuses to even be a part of the process, won’t bring Congress any closer to a resolution,” Brendan Buck said. “The House will take action that reflects the fundamental fact that Americans don’t want a government shutdown and they don’t want the train wreck that is Obamacare.”]

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